Conventionally, to simultaneously make an upper flaskless mold and a lower flaskless mold, for instance, a flaskless molding machine for simultaneously making an upper mold and a lower mold as disclosed in Patent Literature 1 is known.
However, this conventional molding machine involves a problem in which a lower squeeze board is inclined during a squeezing step, and thus the bottom surfaces of the molds to be made are inclined relative to a horizontal plane. In particular, if the profile of a pattern is eccentrically located at one side of a pattern plate, an uneven primary filling of molding sand may increase the tendency to incline. To prevent such an inclination, it may be considered to provide a guide rod to inhibit the inclination of the lower squeeze board. However, this approach involves a problem in that the guide rod may be deformed by the compression force from the squeezing step. Further, a configuration may be complicated by providing the guide rod.
In the conventional flaskless molding machine for simultaneously making the upper and lower molds in Patent Literature 1, it is now assumed that the respective molds are drawn from the mated flasks (“stripping the flasks”) after the molds are completely compressed. In this condition, because the stroke of stripping the flasks equals just the thickness of a match plate and thus it is relatively shorter, it causes the stripped flasks to become unstable. Namely, in this conventional molding machine, after the compression is completed, the lower squeeze board then descends to retract a drag flask and a master plate from the molding position. Then, a squeeze cylinder for setting the flasks ascends such that a stopper pin on the upper surface of a lower filling frame contacts the lower surface of a cope flask. However, because the gap between the upper surface of the drag flask and the lower surface of the cope flask equals just the thickness of the match plate, the maximum length of the cope flask stripping stroke cannot be equal to or greater than the thickness of the match plate. For instance, if the thickness of the match plate is 10 mm, the length of the cope flask stripping stroke is inevitably less than 10 mm.